Yea I definitely need square bellows for what I'm working on. Its one of my homebrew camera designs. Pulling them off of an old enlarger isn't a bad idea. I used to have several sitting around but tossed them last time we did a big cleaning.
I could just make them I suppose. Ian, can you reference any link that you got instructions or a pattern from and also the materials you used. I've made them before but used too thick material so they didn't work out that well.The other option is make some it's not that difficult these are a set I made for my Quarter plate camera, a non tapering set is easier still. Total cost less than $10 and that's with materials left over for more.
Thanks to all for the help!